JP5444545B2 - Cryopump louver extension - Google Patents

Description

(Refer to related applications)
This application claims priority from US Provisional Application No. 61 / 081,461, filed July 17, 2008, the entire contents and disclosure of which are hereby incorporated by reference.

  The present invention relates to a cryopump.

  It relates to a cryopump in the 500 mm to 630 mm size range for a large vacuum chamber used to manufacture solar cells. Large silicon arrays and thin film coatings on a roll of substrate material desorb a large amount of water vapor when they are processed and also require air removal when they are first introduced into the chamber. One or more cryopumps are typically mounted in a vacuum chamber, each cryopump being mounted behind a gate valve, which is vacuumed to remove a bunch of material. When ruptured, it is closed and then the chamber is opened after being evacuated by a mechanical roughing pump to a pressure of about 0.2 Torr.

  A two-stage Gifford-McMahon (GM) refrigerator currently used to cool the cryopump cools the first stage cryopanel to 50-100K and the second stage cryopanel to about 15K. . The expander is usually a stepped cylinder with a valve assembly in the first stage hot section, a first stage cold station in the transition from a larger diameter first stage to a smaller diameter second stage, And a second stage cold station at the far end (at about 15K). A description of the operation of the GM refrigerator can be found in US Pat. No. 3,620,029.

  A cryopump typically has an inlet that is above the axis of the expander cylinder (sometimes called "inline") or perpendicular to the axis of the cylinder (sometimes called "low profile"). Manufactured. The cryopumps used to evacuate water vapor and air in large chambers are typically “in-line”, but the current concept of the invention is equally well applicable to both types.

  Cryo pumps in the size range of 500 mm to 630 mm are commonly used for large vacuum coating chambers. A cryopanel for an in-line cryopump is typically axisymmetric about a cold finger. This panel design is frequently adapted to low profile cryopumps by having a notch in the cold panel for the expander cylinder, as in US Pat. No. 5,156,007. The cryopump operates equally well in all directions with respect to the frozen gas, but during regeneration, the dissolved cryopump adsorbate flows out in different directions depending on the orientation and design of the cryopump.

U.S. Pat. No. 4,150,549 describes a typical cryopump that uses a two-stage GM refrigerator to cool two axisymmetric cryopanels. The first stage cools the inlet (worm) panel, the inlet (warm) panel exhausts Group I gases, eg, H ₂ O and CO ₂ , and a large amount of radiation reaches the second stage (cold) panel. But allows Group II gases, such as Ar and N ₂ , and Group III gases, such as H ₂ and He, to pass through it. Group II gas freezes on the front side of the cup-shaped cold panel and Group III gas is adsorbed in the adsorber on the back side of the cold panel. U.S. Pat. No. 4,530,213 describes a cold panel design consisting of a series of concentric rings having an increasing diameter from the entrance region to the back of the housing.

  It is customary to design the cryopanel, particularly the inlet array, so that it is housed within the cryopump housing. This is true for all of the referenced patents. However, it is not uncommon for cryopanels to be installed inside large chambers such as chambers for testing spacecraft. US Pat. No. 5,819,545 provides an example of a cryopanel cooled by a GM refrigerator that extends into a vacuum chamber. None of these are attached behind the gate valve.

  The main object of the present invention is to adapt a standard size cryopump mounted behind the gate valve to a cryopump with higher pumping speed for Group I by expanding the inlet array to a larger diameter To make it easier to do.

  Larger diameter inlet arrays accommodate either by increasing the diameter of the cryopump housing or by fitting an extension of the inlet array into the space between the cryopump flange and the gate valve disc. Is done. A secondary benefit of the latter option is a small increase in pumping speed for all gases. The extended surface is designed such that a large amount of cryopump adsorbate can be adsorbed before the cryopump is regenerated.

  The flanges described herein are designed as either 500 mm size or 600 mm size according to the International Organization for Standardization (ISO), or 22 "(22 inches) according to the American Standards Association (ASA). Call it.

  In one embodiment, a standard 500 mm size cryopump that can be manufactured with a 22 ″ or 630 mm flange with minimal variation is provided, the cryopump being an exhaust for group I gas proportional to the increase in the inlet area. While having a speed increase, the speed and capacity for Group II and III gases remain unchanged, which is achieved by increasing the diameter of the cryopump inlet array. Increase the diameter of the cryopump housing so that the diameter matches the standard inner diameter of the larger flange, or fit the larger flange to the 500 mm housing and the inlet array with the cryopump flange and gate valve disc Either by expanding into the gap between the For example, a cryopump with a flange of 500 mm to 630 mm is used as an example to illustrate the basic concept of the invention, but other sizes are also available. Applicable.

  In a first aspect of the present invention, a refrigerator having a first stage and a second stage, a cold cryopanel, a worm cryopanel, an inlet array having an extended support bracket extending outside the worm cryopanel, and a housing A cryopump is provided wherein the inlet array fits inside the housing. One or more outer louvers can be provided on a portion of the inlet array that extends outside the warm cryopanel.

  According to a second aspect of the present invention, a refrigerator having a first stage and a second stage, a cold cryopanel, a worm cryopanel, and a housing having a first inner diameter and being fitted close to the worm cryopanel. An inlet array that fits inside the housing, a flange that attaches the housing to a gate valve having a second inner diameter, and a bracket extension that is attached to the inlet array and extends the inlet array over the flange, A cryopump having an inner diameter greater than the first inner diameter is provided.

FIG. 3 is a cross-sectional view of a standard 500 mm cryopump panel and an expander mounted behind a gate valve, with a 500 mm housing, flange, and gate valve shown on the left and configured in accordance with an embodiment of the present invention. The 22 "housing, flange, and gate valve are shown on the right. FIG. 7 is a cross-sectional view of a standard 500 mm cryopump panel, expander, and housing mounted behind a gate valve, with a flange fitting the 500 mm housing to a 22 ”flange shown on the right and a 500 mm housing with a 630 mm flange. Are shown on the left side, both constructed in accordance with embodiments of the present invention, and a standard 500 mm inlet louver is a bracket that fits in the space between the cryopump worm cryopanel and the gate valve disc Shown with an extension. FIG. 5 is a top view of a standard 500 mm cryopump inlet louver array with eight support brackets, showing mounting holes for bracket extensions. FIG. 3B is a side view of FIG. 3A. FIG. 6 is a top view of a bracket extension attached to the end of a standard 500 mm cryopump support bracket, with an annular inlet heel plate attached to the lower surface of the bracket extension. FIG. 4B is a side view of FIG. 4A.

  1 and 2, the cryopump is understood to be axisymmetric as shown in FIG. 3, but for ease of comparison, the cross-sections of the two cryopumps are shown side-by-side. Yes. A broken line separates the two cryopumps.

In an embodiment of the present invention, a cryopump is provided that includes a housing having a larger diameter that can be attached to a non-standard gate valve. The left half of FIG. 1 shows a 500 mm cryopump attached behind the 500 mm gate valve 2a. Some parts are common to all pumps manufactured in this series of pumps and can accommodate different sized gate valves. In the case of FIG. 1, the common or standard components are: first stage heat station 21, expander 20 with second stage heat station 22, cold cryopanel 25, warm cryopanel 26, heat bath 27, and It is a bolt 15. Bolts 15 attach the inlet arrays 10a, 10b to the heat bus 27. The inlet array 10 a for the left structure is composed of a support bracket 13 and a louver 12. In the current design, there are 8 support brackets and 6 louvers, all made of copper or similar materials. Most of the radiant heat incident on the inlet array is conducted to the first stage heat station 21 through the support bracket 13 and the eight copper heat buses 27. The heat bath 27 has a constant cross section and moves most of the heat to the first stage heat station 21. Some heat is also transferred to the first stage heat station 21 through the copper worm panel 26. Only a small portion of the 500 mm gate valve housing 8a is shown along the valve body 7a of the gate valve. "O" ring 9 seals the cryopump flange 17a on the outside of the gate valve housing 8 a, to seal the valve body 7a of the gate valve to the inside of the gate valve housing 8a. A 500 mm cryopump 1a attached to a 500mm gate valve 2a as shown in the left half of FIG. 1 is completed by the addition of a cryopump housing 18a and a flange 17a, which have an inner diameter (ID) of 500 mm.

  The common part of the 500 mm cryopump 1a shown on the left side of FIG. 1 can be incorporated into the 22 ″ cryopump 1b and attached to the 22 ″ gate valve 2b, as shown on the right side of FIG. The inlet array 10 b includes an extension bracket 11, a louver 12, a support bracket 13, and an outer louver 6. Although one outer louver 6 is shown in FIG. 1, in other embodiments of the invention there may be one or more outer louvers. The 22 "gate valve 2b is comprised of a housing 8b, a gate valve valve 7b, and an O-ring 9. The cryopump housing 8b has an ID of 22", as does the 22 "flange 17b. Note that the inlet array 10b is shown within the cryopump housing 18b, including the expansion bracket 11. Also, in Figure 1, on the right side, between the cryopump housing 18b and the worm panel 26. The radial gap is larger than the left radial gap, and the right radial gap is 0.5-3 cm, for example 1-3 cm or 2.5-3 cm.

In an embodiment of the present invention, a cryopump is provided that can be attached to a gate valve having a larger inner diameter than the cryopump housing. FIG. 2 shows a preferred method of constructing a 500 mm cryopump 1a so that the 500mm cryopump 1a can be more easily adapted to a 22 "or 630mm gate valve 2b, 2c. In this design, the cryopump housing 18a and a support bracket 13 having an inlet louver 12 is included within a common component. 500 mm cryopump 1a of this design is Figure in that projecting the inlet array 10 on the flange 17c, 17 d Different from what is shown on the left side of 1. In one embodiment, the inlet array 10 projects above the flanges 17 c , 17 d by less than 3 cm, eg, less than 2.5 cm or less than 2 cm. in the inlet array flange 17 c, it is at least equal to or above the plane of the 17 d. 2, Means according to the present invention to expand the common inlet array 10 to fit within a 22 "gate valve housing 8b as shown on the right side or within a 630mm gate valve housing 8c as shown on the left side. Is shown. The close fit between the cryopump housing 18a and the worm panel 26, for example the radial gap, is typically 2 mm. In one embodiment, due to the close fit, there is no outer louver on the inlet array 10, as shown in FIG.

For the 22 ″ option, the annular inlet scissor plate 5b is attached to the bracket extension 4b, for example by solder, and the bracket extension 4b is then attached to the support bracket 13. The bracket extension 4b is The cryopump flange 17b is non-standard in that it is a 22 "flange with an ID of 500 mm. The expanded inlet array fits within the gap between the cryopump flange 17c and the valve body 7b of the gate valve. In one embodiment, the gap may be 0.5-3 cm, such as 1-3 cm or 2.5-3 cm. The cryopump flanges 17c and 17d in FIG. 2 are greater than 30%, for example, greater than 25% or greater than 23% than the flanges 17a and 17b in FIG.

For the 630 mm option, the annular inlet heel plate 5 c is attached to the bracket extension 4 c, which is then attached to the support bracket 13. The bracket extension 4c may further include one or more outer louvers thereon. The 630 mm gate valve 2 c includes a housing 8 c, a gate valve body 7 c, and an O-ring 9. The cryopump flange 17d is non-standard in that it is a 630mm flange with an ID of 500mm. The expanded inlet array fits within the gap between the cryopump flange 17d and the gate valve disc 7c.

  FIGS. 3A and 3B show a standard 500 mm cryopump inlet louver array 10 consisting of eight support brackets 13 and inlet louvers 12. A mounting hole 14 for the bracket extension is shown in FIG. 3B. This standard array 10 is common to all of the cryopumps shown in FIG.

  4A and 4B show details of the annular inlet scissor plate 5 that is attached to the lower surface of the bracket extension 4, which is then attached to the support bracket 13. The mounting holes 14 in the support 13 and the extension 4 provide a convenient means to attach the bracket extension to the support bracket 13 by bolting them together. In one embodiment, the bracket extension is attached to the support bracket by spot welding or soldering.

  Although a cryopump with a 500 mm to 630 mm flange is used as an example to illustrate the basic outer surface, these concepts are applicable to other sizes. Similarly, although the GM refrigerator has been described as a typical cryogenic refrigerator used in a cryopump, other types such as pulse tube refrigerators or Stirling refrigerators can be used.

1a 500mm cryopump (500 mm cryopump)
1b 22 "cryopump
2a 500mm gate valve
2b 22 "gate valve
2c 630 mm gate valve
4 Bracket extension
4b Bracket extension
5b annular inlet collar plate
5c annular inlet collar plate
6 Outer louver
7a Gate valve (moveable valve plate)
7b Gate valve (moveable valve plate)
7c Gate valve (moveable valve plate)
8 Gate valve housing
8a 500mm gate valve housing
8b 22 "gate valve housing
8c 630 mm gate valve housing (630 mm gate valve housing)
9 O-ring
10a inlet array
10b inlet array
11 Extended bracket
12 louver
13 Support bracket
14 Mounting hole
15 bolt
17a cryopump housing
17b cryopump housing
17c cryopump housing
17d cryopump housing
18a cryopump housing
18b cryopump housing
20 expanders
21 first stage heat station
22 second stage heat station
25 cold cryopanel
26 Warm cryopanel
27 Thermal buss

Claims (8)

A refrigerator having a first stage and a second stage;
Cold cryopanel,
With a warm cryopanel,
An inlet array having a louver, a support that supports the louver, and an extended support bracket that extends outside the worm cryopanel and is separate from the support;
A housing,
The inlet array fits inside the housing except for the expansion support bracket ;
The extended support bracket is attached to the support body,
Cryopump.   The expansion support bracket further includes one or more outer louvers, wherein the one or more outer louvers are part of the expansion support bracket that extends outside the worm cryopanel. The cryopump according to claim 1.   The cryopump of claim 1, wherein the worm cryopanel is designed to fit in close proximity to a smaller housing having a first inner diameter, the housing having a second diameter that is greater than the first inner diameter.   The cryopump according to claim 1, wherein the extended support bracket is attached to the support body by any one of bolting, spot welding, and soldering.   The cryopump according to claim 1, wherein a radial gap between the housing and the worm cryopanel is 0.5 to 3 cm.   The cryopump according to claim 1, wherein the cryopump is attached behind a gate valve having an inner diameter that coincides with the housing.   The cryopump of claim 6, further comprising a flange that attaches the housing to the gate valve.   The cryopump of claim 7, which is mounted behind a gate valve having an inner diameter that coincides with the flange.

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